In various clinical fields including cardiac surgery, orthopedics, neurosurgery, abdominal surgery, and obstetrics and gynecology, it has been a serious problem that after a surgical operation of various types or due to an external injury, tissues in an affected part in a living body adhere to one another. The adhesion of tissues, for instance, can cause pain or impair function, which, if serious, requires another surgical operation for separating the adhering tissues. Moreover, the adhesion also causes a problem of making a follow-up operation with respect to the primary disease difficult. To cope with these problems, conventionally, antiadhesive materials for covering and protecting tissues potentially subject to adhesion have been developed, for the purpose of preventing adhesion of tissues in a living body. A regenerated oxidized cellulose fabric, a hyaluronic acid-carboxymethyl cellulose mixture film, etc., have been in actual use as antiadhesive materials.
More specifically, in order for such an antiadhesive material to perform the antiadhesive function, it is necessary for the antiadhesive material to be present at an application site (affected part) at which adhesion possibly occurs during a required period of time so as to function as a barrier between tissues at the application site, be decomposed finally, and be absorbed in the body. In other words, the antiadhesive material is required to be excellent in biocompatibility, bioabsorbability, and the like.
Even in the case of such an antiadhesive material excellent in biocompatibility and the like as described above, it has to be fixed firmly at the application site so as to perform these functions sufficiently. As a fixing method for this purpose, normally, methods of suturing with a suture thread, bonding with an adhesive, and the like have been used.
However, the conventional antiadhesive material as described above has difficulty in, for instance, performing the antiadhesive function while maintaining its form in a living body for a required period of time, and since it does not have a strength sufficient for durability in suturing, bonding, or the like, it is torn in some cases. Thus, the handling of the antiadhesive material and the fixing of the same at an application site are difficult.
For instance, antiadhesive materials formed with gelatin films excellent in biocompatibility, bioabsorbability, etc., which recently have been studied and developed, and now are in actual use (see JP 11(1999)-239610 A and JP 2000-37450 A, for instance) are inferior in allowing themselves to adhere and fix to surfaces of tissues at an application site. Therefore, for fixing the same at an application site, the suturing and/or bonding methods as described above are used. However, such gelatin films, when applied to tissues, absorb moisture of the tissues and become in a hydrogel state containing water. Therefore, they have a problem of being difficult to fix by suturing, etc.